This project concerns the contribution from one of six centers in a cooperative study begun in 1966 to determine the natural history of three isolated cardiac malformations: ventricular septal defect, aortic stenosis, and pulmonary stenosis. Direct patient involvement in the study terminated in January, 1974. The present proposal requests support for the year 1975 or completion of the extensive data analysis and preparation of results for general medical dissemination, which has been the major effort of the participants in 1974. The main objectives of the study are as follows: (1) to provide means of predicting clinical outlook for any patient with such a malformation, treated medically or surgically, for different grades of serverity at different ages; (2) to provide a basis for evaluating the advisability of surgery in cases where the comparative merits of medical versus surgical treatment are currently in debate; and (3) to provide means of assessing important hemodynamic quantities indirectly, i.e. without cardiac catheterization, on the basis of the electrocardiogram, chest roentgenogram, and clinical findings.